In the related art, an outer frame of a box fan is usually a metal outer frame, and an electric motor support is directly welded to the metal frame. The metal frame is mostly formed of two outer frames of metal materials by means of welding. A rear grill needs to be fixedly connected to the metal frame through ten or more screws.
Thus, there are the following disadvantages existing in the traditional box fan: 1. It is not convenient to weld the electric motor support to the frame, and efficiency of the welding is extremely low; 2. A machining process for the metal outer frame is complicated, and the manufacturability is low; 3. The outer frame structure of metal materials needs to be separately provided with a connecting member to fix an electric component, such that the number of parts is large; 4. An electric motor must be connected to the electric motor support through an adapter, and a screw hole of a metal part additionally needs a tapping process, which results in inconvenient production and processing.